1. Field of the Invention
The present invention relates to a stop control of an internal combustion engine, and particularly relates to a stop position estimating apparatus for estimating a stop position of an internal combustion engine.
2. Description of Related Art
Recently, there is known an engine stop and start control apparatus for automatically stopping an internal combustion engine (hereinafter, also referred to as “engine”) when the vehicle stops and for automatically restarting the engine to start the vehicle when an instruction to start is given in the stopped state, in order to reduce a fuel consumption amount and exhaust gas during idling, from the viewpoint of environmental conservation, resources and energy saving or the like. This control is also called “idling stop” or the like.
It is known that, when the idling stop is automatically carried out, it is effective to control the stop position of the engine in order to minimize required energy at the time of starting the engine. Minimizing the required energy at the time of starting the engine brings about the advantages that an engine starting device used after idling stop such as a motor generator (MG) can be miniaturized, and the useful life of a battery can be elongated by reducing the electric energy.
As a method for controlling the stop position of the engine, there is proposed a method for estimating an engine stop position in consideration of reverse rotation movement at the time of stopping the engine based on the output of a crank angle sensor. For example, see Japanese Patent Application Laid-Open under No. 2002-70629 (hereinafter referred to as Document-1).
As a method related to the stop control of the engine, there is proposed a method for operating a motor generator to stop the engine within a predetermined range, based on an absolute crank angle detected by utilizing a crank angle sensor. For example, see Japanese Patent Application Laid-Open under No. 9-264235.
However, the method for estimating the engine stop position by utilizing only the output of the crank angle sensor, as exemplified in the above-mentioned Document-1, has the problem that the logic of the estimating processing is complicated.